Animals and plants can tolerate only a limited range of environmental conditions. Depending on the species, the ideal range of environmental conditions may be very narrow, particularly during early development. Certain livestock, such as poultry, are commonly housed in a structure with controlled conditions in order to provide the optimal environment for productive and healthy growth. A critical factor for determining the productivity for poultry houses is known as the speed to weight factor, or the time it takes for the poultry to reach the target weight.
Controlling body temperature, or thermoregulation, varies considerably between species of animals, sometimes identified as “warm-blooded”. Young poultry, or chicks for example, have very limited ability to control their own body temperature during the first weeks of development after hatching. To mitigate this problem, when poultry chicks are raised after hatching, the chicks are commonly housed in large structures with ventilation and heating apparatus which is designed to keep the interior at or near 90° F. and to minimize interior humidity. The youngest chicks are sometimes raised in groups, or broods, confined to circular areas in the house known as brooding rings, underneath radiant heat sources known as radiant brooders or pancake brooders.
Environmental humidity has several deleterious effects on the development and health of the chicks in poultry houses. When relative humidity increases, the evaporative capacity of the air decreases. As chicks get older, they are able to lower their body temperature by evaporative heat loss from their lungs. If the chicks overheat, they begin to pant to reduce their core body temperature if unable to do so, they expire from heat stress. Similarly, the floor of the poultry house, or litter, becomes soaked in detritus, including bird waste, which if not allowed to dry by evaporation also negatively affects poultry health. Bacterial growth in the wet litter is known to be the most common source of ammonia gas in poultry houses.
Ammonia gas in a poultry house has been demonstrated to negatively affect chick health and growth. Ventilation of the structure is the common means to reduce ammonia, but this also decreases temperature, which is problematic during cooler months and necessitates frequent use of heating sources and associated costly energy resources. Venting with fresh air is commonly accomplished at fixed intervals for a structure and supplemental heat is provided to account for the infusion of cold air. This process can cause unwanted fluctuations in temperature in the interior of the structure and does not provide any dynamic ability to control interior ammonia.
In the United States, poultry livestock are primarily farmed in the southeastern states, from eastern Texas to North Carolina. Farming is year round in all locations. Widely varying local weather is common throughout the southeast United States sudden changes in weather are common in the spring and fall. This further complicates environmental control of the poultry houses. As mentioned above, during winter months, cold air vented into houses often requires considerable increase in the interior heating for houses with associated fuel costs.
Modern poultry house ventilation systems typically use very large “tunnel fans” which are extremely noisy, causing additional stress and negative health impact on the chicks growing in the poultry house.
Heat, relative humidity, ammonia and noise are several of the factors that can negatively impact both the health and market worthiness of the poultry, as well as the speed to weight for the poultry, or productivity of the house.
Due to the complexity of controlling numerous inputs and monitoring of potentially numerous conditions of poultry house environments, historically the conditions have been controlled manually by the poultry farmer, with warning indicators of extreme conditions. Computerized or automatic control systems have been used with varying degrees of success for several years. Yet numerous unsolved problems remain, including the reduction of energy use for heating and more reliable and effective ways of maintaining a balance of various environmental factors to optimize the conditions for the livestock within the housing structure.